1. Field of the Invention
The present invention relates to an apparatus for discharging some of filter cigarettes from a transportation line to effect removal of defective filter cigarettes or sampling inspection during the manufacture of the filter cigarettes.
2. Description of the Related Art
When a cigarette rod, which is twice as long as a cigarette, is supplied to a filter cigarette manufacturing apparatus or a so-called filter attachment, it is cut into two equal parts or individual cigarettes. Then, a filter plug is supplied between these cigarettes. A paper piece is wound around the two cigarettes and the plug to connect them, thus forming a double filter cigarette. Thereafter, the double filter cigarette is cut in the center into individual filter cigarettes.
As these processes are executed, cigarette elements, such as cigarette rods, cigarettes, double filter cigarettes or single filer cigarettes, are transported continuously on a drum train of the filter attachment. The drum train includes a number of transportation drums, which are arranged continuously with one another, and transportation grooves for receiving the cigarette elements by suction are formed on the outer peripheral surface of each drum. Thus, as the transportation drums of the drum train rotate, the cigarette elements are transported in a manner such that they are delivered between the drums.
In the drum train of the filter attachment, one of the transportation drums for transporting the double or single filter cigarettes is formed as an inspection drum, and another transportation drum which is situated on the downstream side of the inspection drum is formed as a discharge drum. If defective filter cigarettes, double or single, are detected on the inspection drum, these defective are then removed from the discharge drum to the outside of the drum train.
The defectives are removed by supplying transportation grooves of the discharge drum with compressed air whose pressure surpasses the suction pressure. More specifically, each transportation groove of the discharge drum has jet holes. When the transportation groove reaches a predetermined rotational angle zone of the discharge drum, the jet holes are connected to a positive-pressure line in the discharge drum, whereby the compressed air is ejected from the jet holes to remove the defectives from the transportation grooves.
The positive-pressure line is provided with a solenoid valve in the middle. This valve closes the line when non-defectives in the transportation grooves pass the aforesaid rotational angle zone. In this case, therefore, the compressed air cannot be ejected from the jet holes of those transportation grooves, so that the non-defectives are transferred from the discharge drum to the next transportation drum.
According to this method of removing defectives, the compressed air must be ejected from the jet holes of each transportation groove of the discharge drum only when tills transportation groove passes the aforesaid rotational angle zone. If the start of the ejection of the compressed air from the jet holes is lagged, non-defectives, not defectives, in the subsequent transportation grooves will inevitably be removed. If the termination of the ejection of the compressed air is lagged, on the other hand, the non-defective in the subsequent transportation groove, as well as the defectives, will be removed in vain.
Accordingly, the solenoid valve requires high-speed switching operation. In modern high-speed versions of filter attachments, however, the speed of transportation of filter cigarettes on each transportation drum or the discharge drum is too high for the switching operation of the solenold valve to follow, so that defectives cannot be accurately removed.
Even though satisfactory responsiveness is secured for the switching operation of the solenoid valve itself, moreover, the valve-open period of this valve is very short. Therefore, a positive pressure cannot be adequately raised in the jet holes of each transportation groove, so that the ejection pressure of the compressed air is lowered. Thus, the defectives cannot be properly removed from the transportation grooves.